Porous materials are widely used in biomedical, industrial, and household applications. In the biomedical field, porous materials have been used as scaffolds (templates) for tissue engineering/regeneration, wound dressings, drug release matrices, membranes for separations and filtration, sterile filters, artificial kidneys, absorbents, hemostatic devices, and the like. In various industrial and household applications, porous materials have been used as insulating materials, packaging materials, impact absorbers, liquid or gas aborbents, membranes, filters and so forth.
Implantable medical devices frequently induce a foreign body response that results in the formation of an avascular, fibrous capsule around the implant, which limits the performance of the device. For example, formation of these fibrous capsules can result in capsular contracture, the tightening and hardening of the capsule that surrounds the implanted device. Capsular contractions not only distort the aesthetic appearance of the surrounding are where the implant is placed, but also cause pain to the individual. Problems with capsular formation and contracture occur in many types of implantable medical devices, such as, e.g., pacemakers, orthopedic joint prosthetics, dura matter substitutes, implantable cardiac defibrillators, tissue expanders, and tissue implants used for prosthetic, reconstructive, or aesthetic purposes, like breast implants, muscle implants, or implants that reduce or prevent scarring. Correction of capsular contracture may require surgical removal or release of the capsule, or removal and possible replacement of the device itself.
Scar tissue formation in the healing of a wound or surgical incision is also a process involving the formation of fibrous tissue. A visible scar results from this healing process because the fibrous tissue is aligned in one direction. However, it is often aesthetically desirable to prevent scar formation, especially in certain types of plastic surgery.
The biological response to implantable medical devices and wound healing appears dependent on the microarchitecture of the surface of the implants. Implants with smooth surfaces in particular are most susceptible to capsular formation and contracture. One means of reducing capsular formation and contracture has been to texture the surface of an implantable medical device. In these methods, a textured surface is imprinted onto the surface of a device forming “hills” and “valleys” architecture. See, e.g., U.S. Pat. No. 4,960,425, Textured Surface Prosthesis Implants; U.S. Pat. No. 5,022,942, Method of Making Textured Surface Prosthesis Implants. However, capsular contracture can still occur in implantable medical devices textured in that manner.
In addition, medical devices for implantation within a patient's gastrointestinal tract are typically anchored in place with sutures or other barbs. Capsular contracture is typically a remote issue for such kinds of implantation. However, such implantation methods may cause an adverse effect in the patient's body, such as a prolonged puncture or penetration of the gastrointestinal tract. It is thus desirable to produce a less invasive manner of fixing implantable devices within the gastrointestinal tract.